Typically, a corner bead for trimming a drywall corner has a central portion with two lateral edges and two flange portions, each extending from one of the lateral edges of the central portion. It is known to make a corner bead from paper, plastic, such as polyvinyl chloride, or metal, such as galvanized steel, so as to have unitary central and flange portions. Typically, if the corner bead is extruded from polyvinyl chloride, the flange portions have thicknesses in a range from about 0.035 inch to about 0.050 inch. The flange portions may be initially attached to the underlying drywall via staples or via a sprayed-on adhesive.
Moreover, it is known to provide the flange portions with an array of apertures, either circular holes or elongate slots, whereby drywall-finishing material, joint cement, or like material, when pressed onto the outer surfaces of the flange portions when the corner bead is used, can be thus pressed through the apertures, into intimate contact with the underlying drywall. When pressed through the apertures, into intimate contact therewith, such material bonds with and helps to attach the corner bead to the underlying drywall.
Commonly, the central portion has an arcuate profile and defines a convex surface and a concave surface, whereupon one of the convex and concave surfaces becomes an outer surface when the corner bead is used. If the concave surface has a large radius, such as a radius within a range from about 0.375 inch to about 1.5 inches, it is known to refer to the corner bead as a "bullnose" corner bead.
Weldy U.S. Pat. No. Re. 34,547 discloses various corner beads, two-way corners, and three-way corners of related interest. Having a central portion with an arcuate profile and having two flange portions, each branch of a two-way or three-way corner is similar to a short length of a corner bead, as discussed above.
As exemplified in Australian Patent Specification No. 153,625, circa 1953, and in Ritchie et al. U.S. Pat. No. 5,131,198, it is known to cover a corner bead, which is made of plastic or metal, with a paper layer extending beyond the flange portions of the corner bead. The Ritchie et al. patent discloses a protective coating, which contains an acrylic resin and which is applied over the paper layer where the paper layer covers the central portion of the corner bead, before the corner bead is used.
Conboy U.S. Pat. No. 5,418,027 discloses a plastic tape for taping a wallboard joint. The plastic tape has a center segment, which is rolled or embossed so as to facilitate bending or folding of the plastic tape, and has discrete fibers adhering to both of its expansive surfaces. The plastic tape has a thickness ranging from about 0.015 inch to about 0.020 inch, preferably about 0.017 inch. Being known as floc, the fibers can be nylon, rayon, polyester, cotton or other cellulose, or other similar fibers or combinations of fibers and have preferred lengths ranging from about 0.005 inch to about 0.030 inch. The fibers are used to adhere a taping compound to the plastic tape.
Bergin U.S. Pat. No. 5,544,463 discloses a corner bead of related interest. The corner bead, which is described as prefinished, has a recessed face, which is defined by the joints where the central portion and the flanged portions are joined, and a veneer strip, which is configured to fit into the recessed face. The veneer strip may be formed of wood, foils, metals, or plastics or a plastic or enamel veneer is used.
This invention has resulted from ongoing efforts to improve drywall-trimming articles, particularly but not exclusively corner beads and particularly but not exclusively drywall-trimming articles made from polymeric materials, such as polyvinyl chloride.